Answer:
a. heart development.
Explanation:
As the third week of fetal development starts, the process of formation of blood vessels begins. Also, the splanchnic mesoderm in the head end of the embryo forms heart on days 18 and 19. Since it develops heart, this part of the mesodermal cells is called the cardiogenic area. The underlying endoderm sends the induction signals to these mesodermal cells to form a pair of endocardial tubes that gradually develop into a single primitive heart tube.
This primitive heart begins to beat by the end of the third week of development. Therefore, any drug that affects fetal development during the first 20 days of the pregnancy might affect the development of the heart.
The part of a DNA molecule responsible for the direct coding of specific traits in an organism is the nucleotide sequence.
<h3>How is a DNA molecule structured?</h3>
The DNA molecule is the biological molecule that stores genetic information in living organisms.
The DNA molecule is made up of three major components in its structure:
- Five carbon sugar
- Nucleotide bases
- Phosphate group
The five carbon sugar is deoxyribose while the nucleotide bases are four in number as follows:
- Adenine
- Guanine
- Thymine
- Cytosine
These nucleotides are responsible for the direct coding of specific traits in an organism.
Learn more about DNA at: brainly.com/question/13541376
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Answer: The genotype ratio of offsprings of a cross between one homozygous tall plant and one heterozygous tall plant is 2TT:2Tt
The phenotype ratio is that all offsprings will be tall.
The genotype ratio of a cross between two heterozygous red flowers is 1RR:2Rr:2rr. The phenotype ratio is 3 Red flowers: 1 white flower.
Explanation: From the information given, tall is dominant and short is recessive while red is dominant and white is recessive.
Let T represent the allele for tall height, t represent the allele for short height, R represent allele for red flowers and r represent allele for white flowers.
The genotype of a homozygous tall plant is TT, the genotype of a heterozygous tall plant is Tt, the genotype of a heterozygous red flowered plant is Rr.
The possible genotypes of offsprings of a cross between one homozygous tall plant and one heterozygous tall plant are TT and Tt.
Tt will manifest outwardly as tall because T is dominant over t. Therefore, all the offsprings will be tall.
The possible genotypes of a cross between two heterozygous red flowers are RR, Rr and rr. RR will manifest as red, Rr will also manifest as red because R is dominant to r while rr will manifest as white because white allele (r) is recessive. Therefore 3 plants will be red-flowered while 1 plant will be white flowered.
See the attached punnet squares for details of the cross.
2,8,6
lol just use google